It is known in the industry to use braided sleeving to form rigid tubular parts. The braided sleeving is typically impregnated with a res in and then slipped over a mold or mandrel then subjected to heat and pressure to form a tubular part. The formed rigid tubular part is then removed from the mold or mandrel.
U.S. Pat. No. 5,409,651 issued to the assignee of the present application discloses a method of forming a tapered tubular part made from braided sleeving, the entire substance of which is hereby incorporated by reference herein as if fully set forth in its entirety. The braided sleeve is placed into a mold and then a tapered mandrel is inserted into the mold. Heat and pressure applied to the sleeve cause the filaments of the sleeve to fuse together. The sleeve is then cooled and a rigid tapered tubular part is removed from the mandrel. The sleeve may be bi-axial braid or tri-axial braid. Bi-axial braid comprises two groups of filaments which criss-cross one another and are interwoven together in an over, under pattern. Each filament is positioned at an angle to the longitudinal axis of the sleeve. This patent discloses the sleeving as being an over one under one diamond bi-axial braid pattern or a over two under two bi-axial braid pattern.
U.S. Pat. No. 4,774,043 also discloses the use of a bi-axial braided sleeve to form a reinforced plastic part by placing the sleeve over a mold and then impregnating the sleeve with settable plastic. The mold of this patent has a middle region having a relatively small or reduced diameter and two opposing end regions with a larger diameter than the middle region. The fibers which make up the sleeve are impregnated with a settable plastic which when heated and then cooled, hardens to form a fiber reinforced plastic part. This patent discloses a bi-axial braided sleeve and does not disclose the use of a tri-axial braided sleeve.
In addition to tubular sleeves being made out of bi-axial filaments extending in two different directions criss-crossing one another, tubular sleeves may also be made out of tri-axial braiding. Tri-axial braid is preferable to bi-axial braid because it produces a finished part which has mechanical properties, such as strength and stiffness, which are superior to that of a part produced from bi-axial braid. Tri-axial braid comprises first and second criss-crossing yarn filaments braided together as in a bi-axial braid but in addition, comprises longitudinally extending filaments which are braided into and out of the first and second criss-crossing filaments. Tri-axial braided sleeves are disclosed in U.S. Pat. Nos. 2,114,274 and 4,741,087. The longitudinal fibers or filaments are responsible for the increased quality of the mechanical properties.
One problem with tri-axial yarn is that it is not stretchable longitudinally and transversely to the longitudinal axis of the sleeve. On the other hand, bi-axial braided sleeving is stretchable both longitudinally and radially. If expanded longitudinally, a bi-axial braid will contract radially or if the bi-axial braided sleeve is expanded radially, it will contract longitudinally. Thus, bi-axial braid can be utilized to form tubular parts having varying cross-sections, i.e. alternatively smaller and larger cross-sections or diameters, because the bi-axial braid has the ability to expand and contract radially so as to conform to a mold of this shape. On the other hand, tri-axial braid does not have this ability.
Therefore, it would be desirable to combine the ability of bi-axial braid to conform to a mold having varying cross-sections with the superior mechanical properties of tri-axial braid.
Therefore, it has been one objective the present invention to provide a tubular braided sleeve of a tri-axial configuration which is expandable in a radial direction in order to be slipped over a mold of varying cross-sections.
It has been another objective of the present invention to provide a method of making a tubular part of differing cross-sections from this type of tri-axial braided sleeving.
It has been yet another objective of the present invention to provide an article of manufacture made from this type of tri-axial tubular braided sleeving.